Electrical timing apparatus



Aug. 3, 1937. 'r. P. PREIST ELECTRICAL TIMING APPARATUS Filed on. 12,1934 3 Sheets-Sheet l A TTORNE Y5 Aug. 3, 1937. 'r. P. PREIST ELECTRICALTIM ING APPARATUS 5 Sheets-Sheet 2 Filed Oct. 12, l934 Aug. 3, 1937. 'r.P. PREIST ELECTRICAL TIMING APPARATUS Filed Oct. 12, 1934 5sheets-sheets 0 O O 0 Q O O O O D O O OD 0 o o o a o o a o INVENTOR7710/1445 pH/L/P Pei/5r 6m 6m A TTORNEYJ Patented Aug. 3, 1937ELECTRICAL TIMING APPARATUS Thomas Philip Preist, Wallasey, England,assign or, by mesne assignments, to Automatic Tclempany Limited, London,

phone & Electric Co England Application October 12, 1934, Serial No.748,067

In Great Britain October 14, 1933 12 Claims.

The present invention relates to electrical timing arrangements for usewith trafliccontrol signals employed at .road Junctions or the like andmore particularly systems employing controllers 5 of the type in whichthe display of the signals is controlled by the trafllc passing over theroads in question, for instance by means oi contactmaklng pads let, intothe road surface. The invention .moreover is particularly applicable to10 systems of the type in which the timing of the various intervals isefiected by a condenser which is shunted by a neon lamp in series with arelay,

the resistance of the charging circuit being adjustable so that the timetaken for a condenser 15 to charge to the striking voltage of the lampmay be' varied.

A system illustrating one arrangement of this invention is disclosed inBritish specification No.

403,732 and portions 01' the specification describ- 2o ing thisarrangement are included in the following material. v

The system described in specification #403,732 relates to trailiccontrol signals for use at road crossings or the like and is moreparticularly con- 25 cerned with a progressivetype traflic controlsystem by means 01' which a number of controllers located at successiveintersections at a main road may be regulated from a master controllerin a certain phase relationship to each other, so that 30 it the averagespeed of the traiilc is known it is possible to time the control signalsso as to ensure a substantially continuous flow or traiiic along themain The arrangement moreover is particularly concerned with systems inwhich the operation oi the signals may be controlled in accordance withthe density, of the traflic by the employment 01 vehicle detectorslocated in the roadway.

In such systems the actuation of vehicle de- 40 tectors bytraiiicapproachinga right 01' way signal is arranged to prolong the timeof display of such signal, and the amount of such prolongationmaybemadeto'varyinverselyasthespeedotthe actuating traflic. The system01' the British speciiication referred to i'or example, employs thecharging oiv an electric condenser to the flash voltage of a dischargetube for timingthe right way signal period and the speed variableprolongation oi' such period isobtained by partial 50 discharge ci'thecondenser by traiilc actuation,

the amount of such partial discharge i'rom any degree of charge belowthe flash voltage being dependent on the. time iensth of trafllcactuation. 'Since the latter can.be made substantially in- 55 verselyproportionalto the speed of actuating traiiic the amount of dischargealso varies inversely in speed. The condenser discharge tube timeremployed may be termed an electrostatic timer.

In this system the termination of the right of way period when thecondenser is charged above the flash or threshold voltage 01' thedischarge tube is controlled bytrams actuation on the crossing roadwaywhen the latter does not have right of way, such crossing traflicactuation compieting a circuit for discharge of the condenser throughthe discharge tube in case the condenser voltage is above the thresholdvalue. The supply voltage for charging the condenser is considerablyhigher than the threshold voltage of the tube, so that in the absence oitraflic actuation on both intersecting roadways for an appreciable timethe voltage on the condenser-will rise considerably above the thresholdvalue. Under these circumstances it will be appreciated that actuationby a very fast vehicle approaching a right of way signal might notdischarge the condenser below the threshold value and thus might notproperly assure a prolongation of the right of way period.

The present invention provides an arrangement particularly adapted toelectrostatic timers for causing substantially instantaneous dischargeof the condenser to just below the threshold voltage in case thecondenser has been charged above the threshold voltage when a prolongingactuation occurs. This rapid discharge is then cut oil! somewhat belowthe threshold voltage so that discharge below this point will be closelyproportional inversely to the speed of trafllc. It will be obvious tothose skilled in the art that the invention is not limited to thespecific type 01 electrostatic timer illustrated in this embodiment, butthat other types of tubes might be used for example or other within thescope of the invention.

Thus it is an object of this invention to provide in an electric timeremploying the varying of charge on a condenser over aperiod 0! time tothe threshold voltage operating value 0! a charge responsive deviceandha-Ving provision for partial reset oi the charge on said condenserby momcntary operation oia discharge circuit to prolong the time periodof .the timer, an arrangement for assuring reset of the charge on thecondenser changes in the timing apparatus might be made from any pointabove the threshold value at least down below such value on anyresetting operation of the discharge circuit occurring when the chargeon the condenser is' above such threshold value. It is also an object01' invention to provide a timing apparatus actuatable- !or partialreset- 66 ting its time period in which any momentagy actuation of anyappreciable length will reset the timer to at least a minimum extent.

An additional object of the invention is to v timing phase relation of aplurality of local inter- I section trafllc signal controllers. Figure 2shows one form 01' local intersection controller in connection .with aset of relays operated by the master controller. Figures 1 and 2 takentogether show one form of master-local control arrangement as describedin the British specification. Figure 3 shows a modification of the localcontroller oi the general type in Figure 2, in whichmodiilcationprovision is made for operating the local controller byvehicle actuation. Figure 4 shows a modification of Figure 3 made inaccordance with the invention. Figure 5 shows incompact tom theessential elements of the timing arrangement illustrating the inventionas taken from Figure 3 and including the modification shown in Figure 4.

The system shown in Figs. 1 and 2 does not make use or vehicle detectorsto regulate the timing of the signals but its operation will bedescribed in order to permit a proper understanding of the systemillustrated in Fig. 3 in which vehicle detectors are employed.

40 It should be explained generally that the system illustrated in Figs.1 and 2 comprises a master timer, from which separate pairs ofconductors radiate to each controller for the purpose ofregulating'their time periods in relation 46 to each other. Thecontrollers in one embodiment may be conveniently arranged to operate atfixed time periods independent 01' the trafllc flow, that is to say,there is no question of extending their normal period as a result of aso continuous flow oi tramc passing over a road contact or the like.These controllers will be set to operate at rather long periods,considerably in excess of that required in the progressive system, butthe periods will be curtailed by the right amount upon'the reception ofso-called light" and "heavy" pulses over the control'leads from themaster timer.

v Reierring now to the circuit'shown, the system is arranged foroperation from A. C. mains and oosuitable rectifying arrangements areprovided for obtaining direct current to operate the relays and neonlamps. In the drawings the alternating currentmains designated Ill andII are shown incoming from the left hand side of Fig. 1

and for the operation of the master. timer a tapping is made from theseleads by way oi'the fuses FUS and main switches MNS to the primarywinding, of the transformer XFR. This transformer is provided with threesecondary windings two of which connect with the thermionic valveamplifier VLV which. supplies direct current or the order of 400 voltsto theterminals designated and --in a circle, for the purpose oi.

flashing the neon lamp N. The third winding on .15 the secondary.side-oi the transformer XFR con- 2,oes,72s

Y nects with the full wave metal rectifier bridge troller No. 3, whichis not shown as it is asclose contact springs in a particular order. Asregards the No. 2 controller shown in Fig. 2 it .should be explainedthat the cam shaft is rotated MRA which supplies direct current of theorder of 50 volts to the terminal points marked and in a square, for thepurpose of operating the relay F and the driving magnet DSM. Essentiallythe master timer comprises a rotary stepby step switch DST of the typeused inautomatic telephone systems which is completely immersed inoil'and arranged to be operated step by step from a neon lamp impulser,the speed of which may be altered, byvarying the setting of theresistance switch i2 connected in serieswith the condenser QB."

As regards the automatic stepping circuit it should be explained thatwhen the neon lamp N flashes as the result of the charging of thecondenser QB to the required voltage, relay E is operated in seriestherewith, thereby at armature el operating relay F, andat armature e2connecting negative potential to the wipers of the switch DST. Relay Fon operating, at armature f2 completes the circuit for the 4drivingmagnet DSM, at armature ,fl supplem' ts the connection to the wipers ofthe switch ST, at armature ji-shunts the neon lamp N and relay E by wayor resistance YB and at armature fl flashes the master fail alarm lampMFA. Relay E thereupon releases and upon the release of relay F afterits slow period due to the copper sing on its core, the driving magnetis de-energized to advance the wipers on to the next set of bankcontacts. This action continues automatically so long as the system isin service. One bank and wiper oi the switch DST is allotted to eachcontroller to be regulated and the control leads extend from theappropriate contacts in the associated bank. Bank la connects withcontroller No. 1 of which only the regulating. relays have been shown inthe dotted rectangle; this controller may be located adjacent to themaster timer; Bank 20 connects with controller No. 2 shown in Fig. 2,and bank 3a connects with consumed. to be identical with controller No.2.

In the drawings each control lead is shown as making two connectionswith its associated bank, one of which is direct and the other extendsby way oi a resistance. Consequently as the switch rotates so-calledlight and'heavy pulses are delivered over the control leads to therespective controllers in turn.

The control leads may comprise light gauge wires, ior example telephonelines, and terminate in the controllers on a pair of relays B and Cshown in Fig. 2 connected in series, one or which is marginal. As aresult of the operation of one or both of these relays from the lightand heavy pulses the signal lights of the controller are reg- I ulatedaccordinglyr In this'particular example the complete cycle time or thesystemis represented by 25 steps of the rotary switch DST in the mastertimer. Each step of the switch therefore represents 4% of the totalcycle time so that -by varying the connection oi the control leads tothe banks the phase relationship between the diflerent sets at controlsignals may. be adjusted to a very fine Each of, the controllers, whichare all identical, comprises essentially a battery or cams mounted on acommon shaft and arranged to step by step under the'control of asolenoid S which is impulsed at predetermined time periods from a neonlamp' timing device, comprising the lamp IN and impulse relay A. The camassembly is moreover, a standard unit which may 5 be used in differentcircumstances and controls 22 spring sets with six difi'erent positions.full number 'of cams is not employed in the present instance and the.chart shown in Fig. 2

shows the effect of the various cams which are used in this particulararrangement. The cam contacts which areclosed in each of the sixpositions are designated in the chart by a heavy black circle or line.If it is assumed with regard to controller No. 2 ".5 that the cam shaftis in its first position, cam contacts CI, C9 and C22 will be operated,thereby lighting the green signal lamps GNS for the north-south road,and the red signal lamps REW for the east-west road, while at the sametime over cam contacts CI, a circuit is complete from the valverectifier IVLV by way of a tapping on the common resistance I3 forcharging the condenser QA: After the initial period of for example 10seconds has elapsed, the con- 25 denser QA will be charged suflicientlyto cause the neon lamp IN to flash over, thereby operating relay A whichat armature aI energizes the solenoid S which advances the cam shaftinto its second position. In this position, as will be evident from thechart, the signal lamps already lit are maintained and over cam springsC2 and the adjusting switch shown a charging circuit is connected incircuit in this position must be 40 very high to ensure that thecondenser charges slowly, and for this reason the adjusting switch C2 inquestion is preferably turned round into its extreme position where it.will be understood that it connects with the end of the common 46resistance shown.

During progressive working this particular timing circuit 'will havepractically no effect on the operation of the controller since with thenormal operation of the master timer a light pulse is 50 delivered overthe control leads before it becomes operative. As alreadyexplainedthis'light pulse is obtained by including a high resistance in the pulseleads at the banks of the master.

timer, and as a result relay B only is operated in the controller,thereupon at its armature M in conjunction with the cam contacts 01com.- pletinga low resistance charging circuit for the condenser QA.Almost immediately therefore the neon lamp IN flashes and causes thecontroller to step to position 3. Non-inductive resistances areconnected across the control leads as shown in order to guard againstfalse operation owing to surges and inductive discharges. v

- In accordance with the change of the cam contacts, the green lightsfor the north-south road are now replaced with amber lights ANS, andover cam contacts C3 and the adjustable resistance switch a circuit iscompleted for the 70 condenser QA to control the duration of the ambersignal. with this arrangement although the phase of the amber signal maybe changed when an adjustment is made in the cycle at the master timer,its actual duration remains constantsince 15 it is determined by thesetting of the 19011 adjusting switches and is not influenced by therelays connected to the control leads. In case it should be desired toshow the amber signal simultaneously to both roads, as is therequirement of certain administrations, this may II be achieved bybridging the amber circuits by means of the strap II shown dotted in thedrawings. After the duration of the amber warning period the solenoid Sagain operates to step the cam shaft to position 4 and the controlsignals 10 are then completely reversed while over cam springs Cl acharging circuit .is completed for,

the condenser QA which provides an initial timcontroller during normalprogressive operation since a heavy pulse will be received from themaster timer meanwhile, which results in the operation of both relays Band C, and the latter at armature cI in conjunction with the camcontacts CI! steps the cam shaft into its final 30 position 6. In thismanner the controllers are stepped progressively depending on theconnections to the banks of the timing switch, and providing the mastertimer is functioning correctly, the time periods of their stop" and gosig- 35 nals will be directly regulated therefrom.

If however for any reason the master timer should fail in such a mannerthat no further impulses are delivered over the control leads, theindividual controllers will continue to function *0 satisfactorily atsomewhat longer time intervals as a result of the chargingcircuitscompleted over the cam contacts C2 and C5. Moreover in case a.particular line fault on the control conductors should maintain'operatedone or both of I the signal relays at the controller, the latter willcontinue to function at somewhat shorter time intervals as determined bythe initial timing circuit completed over cam contacts CI and 50 Cl.

In addition to the normal operation of the system and the necessarysafeguard against failure, it is also possible to provide specialfeatures such as for example causing all controllers to show a redsignal to'all approaches thereby ef- 55 fecting a complete hold up ofthe traflic. This condition may be brought about instantaneously fromthe master timer by the operation of the manual switch which closes thecontact marked 'ARS in the drawings, thereby connecting poten- 60 tialto a common wire I5 extending to all controllers which results in theoperation of a relay -AR in each. Relay AR at armature arI disconnectsthe operating circuit for the controller which is thus brought to restin the position to which it is set, at armature 111:2 opens the circultof the green and amber signal lamps and at armature or! bridges thecircuit of the red signal lamps so that both sets are lighted. It willbe appreciated from a consideration of the chart that in all positionsof the controller one or other of the red signals will be showing'andtherefore, the connection described will be effective no matter in whatposition the controller is brought to rut. Tl

For the purpose of switching the controllers on and off a further commonwire ii is provided which connects with the switch contact C583 atthemaster point and a relay CS'in each controller. The operation of themanual switch to a second position disconnects themaster timer insofaras its control function is concerned by opening the circuit to the valverectifier VLV at springs CSSI. and C882, and atsprings CSSI connectspotential to the common lead ii to operate a relay CS in allcontrollers, which thereupon at armatures csl disconnect the respectivecontrollers from the alternating current mains. This method of controlis preferred to the alternative, whereby the relay is operated toconnect'up the controller since, a failure at the master timer mightthen result in the individual controllers becoming disconnected. .In afurther position of the manual switch springs CSSland CSS! are openedbutsprings CSSl are not closed. In these circumstances the mastercontroller no longer sends pulses but the individual controllers are notswitched off and continue to operate independently.

Arrangements are also provided by means of a special manual switch ateach controller whereby the all red feature may be brought into actionat that particular point only. When this manual key is operated, thesprings ARSI and ABS! are actuated, thereby disconnecting the circuitfor the green and amber signal lamps and also connecting together thered signal lamps so that both sets show simultaneously regardless of theposition of the controller.

In case it should become necessary under certain circumstancesefor aparticular controller to be operated manually, the required circuitchanges are brought about by the operation of a furtherkey whichactuates the springs MANI 40 and MAN! to disconnect the timing circuitof the controller and also connects the solenoid S .in circuit with apush button PB. The operation of the push button by the omcer in chargecauses the controller to step through its cycle and any desired timeperiods may be allowed.

- As already explained, a supervisory lamp MFA is provided which islocated in a conspicuous position at the master timer and arranged toflash in synchronism with the stepping switch. Any

o abnormal condition. such as the blowing of the mainfuse or failure ofindicated by to light. J

In case the master timer is switched on at a the neon lamp will be thefailure of the supervisory lamp time when certain of the controllers areout of a phase, the correct phase setting between each will be restoredwhen the stepping switch in the master timer has made one completerevolution.

Considering now the arrangement of another Bo embodiment of thecontroller illustrated in Figure 3, this represents the equipment at anindividual controller which is intended to perform similar functions tothat illustrated in Fig. 2, but is designed for actuation by traflic. Itwill be appreciated however that the current supply arrangements areshown somewhat differently and also that where complete remote controlof the corresponding functions is desired relays such as CS, AR and Cwill still be required to respond to 70 signals from the mastercontroller. In this illustration relays CS and AR are'omitted and themaster controller need send only one controlim- "pulse per cycle whichoperates relay 0' corre sponding to relay C in Fig. 2. The controller of7 Fig. 3 is of the same construction as lamps.

that illustrated in Fig. 2, that is to say, it is provided with a numberof sets of contacts operated by a cam shaft which is moved step by stepby means of a solenoid. Moreover, the stepping of the solenoid is againcontrolled from a timing circuit employing a neon lamp condensercombination but in this case the timing is variable under the control ofvehicle detectors located in the roadway. cults are employed and tworoad relays are provided which respond to the passage of vehicles overthe detectors. In view of the description which has already been givenit will not be necessary to describe in considerable detail the workingof the apparatus illustrated in Fig. 3 but the more salient features ofoperation will be considered briefly.

The current supply is assumed to be taken from alterrfatin'g currentmains and is rectified to pro-' vide direct current for the operation ofthe neon The transformer LXFR. feeds the valve rectifier VB and alsosupplies alternating current of a suitably reduced voltage for theoperation of the road relays. The live pole of the A. .C. circuits isrepresented by a plus in a circle, the live pole of the D. C. circuitsby a plus in a squareand the'common earthed pole by a minus in a circleand a square. The chart shows as before the positions of the cam shaftin which the various cam contacts are closed. The various intervaladjusting switches INS, VNS, IEW, VEW. LNS, LEW are wired to appropriatetapping points of the resistance 20, and similarly the switches MNS andMEW are wired to resistance II which gives tappings of higher value.

For convenience of description it will be assumed first of all that thecam shaft is-standing in position 6 giving right of way to the street NSand that there is no traffic on either street. In these circumstances acharging circuit is completed over contacts Cl and the adjusting switchVNS for the condenser QJ, but owing to the fact that neither relay D norrelay E is operated, it

.is impossible for discharge to take place through the neon lamp FJ whenthe condenser becomes charged to the striking voltage. However, no

Suppose now that a vehicle arrives on the road EW, relay D will beenergized due to the operation of a detector DEW and since contacts 06are closed, a circuit is completed over armature d2 and contacts Ci forstriking lamp FJ so that.

relay J, is energized and the solenoid is operated at armature ii and.the cam shaft is moved to position I. In this position the lamp ANS islightedin' place ofGNS and lamp'AEW is lighted in addition to lamp REWif the dotted connection is used. Moreover, a new charging circuit iscompleted for condenser QJ over cam contacts Oil, the adjustingswitch'LNS and the appropriate chargingresistance. Relay D moreover waslocked up over armature d! and contacts C1 so that as soon as thecondenser QJ has been charged sufliciently, which will occur after afewseconds only, relay J is again operated and advances the cam shaft toposition 1. In thisposition lamps GEW and RNS only are lighted and thevehicle in the street EW secures right of way.

Furthermore a new charging circuit is now com pleted for condenser QJ,this time over contact on and switch nrw. Consequently. after the periodcorresponding to the resistance now included in the charging circuit,relay J is again operated and the solenoid steps the cam shaft toposition 3. This produces no change in the lights but the chargingcircuit for condenser QJ now extends over contact -CI5 and the switch'VEW and moreover relay D is dc-energized by the opening of contacts C1while owing to the closure of contact CIG a circuit is prepared forshunting condenser QJ. If there is no further traflic, right or way willremain on the EW road and the condenser QJ will become fully charged.

= If iurther vehicles arrive on the EW road however relay D is againoperated and shunts the condenser by way of the comparatively lowresistance YE, cam contacts CIS and armature d2 and thus extends thetime which will be required for the condenser to be charged to thestriking voltage of the lamp FJ. It may bepointed out that since inthese circumstances relay D is only operated while the vehicle isactually passing over the detector pad, the amount of extension obtainedis dependent on the speed of the vehicle, being greater for a slowmoving vehicle than for a fast moving one.

11 now a vehicle should arrive'on the road NS, relay E will be operatedand locked and contacts C" will complete a circuit for eflecting theoperation of relay J as soon as condenser QJ is sumlength to permit thestriking voltage of the neon lamp FJ to be reached occurs in the trafllcon, the road EW, relay J will be operated and will advance the cam shaftto positions 4, 5, and 6 in turn in the manner to be described to giveright or way to the road NS.

In case, however, the traflic on the road EW should be substantiallycontinuous, that is to say, there should be no break sufliciently longto permit condenser QJ to charge up, the maximum timing circuitinvolving the condenser QK comes into operation. It will be noted thatthis circuit comes into operation as soon as there is a waiting vehicleon the road NS at which time relay E is operated and locks up overcontacts CIB. The charging circuit for condenser QK now extends overcontacts Cl! and the switch MEW condenser QK, thence overcam contactsCl! and armature e2 by means of which a resistance 2| is connected incircuit which will permit the condenser QK tocharge up only after aninterval considerably greater than that required for the charging ofcondenser QJ.

In position 4 of the cam shaft cams CH1 and C22 are operated to displayNS red and EW amber signal. A charging circuit overcam contacts C2,adjusting switch EEW "and the appropriate charging resistance builds upthe charge on condenser QJ to the striking voltage or thresholdconducting 0 E. M. F. of the lamp FJ. The momentary current flowing thruthe lamp FJ energizes relay J which at armature 1| completes a circuitto operate solenoid S, which advances the cam shaft to position 5.

In positions 5 and 6 lamps GNS and REW are lighted to accord right ofway to NS traflic. The charging circuit for condenser QJ in position 5is completed over cam contacts C3 and switch INS. After the periodcorresponding to. the resistance now included in the charging circuithas elapsed,

relay J is again operated and the solenoid ad- .vances the cam shaft toposition 6, the NS vehicle interval, thuscqmpleting one cycle on the camshaft. 1

In position 8 relay E is not held. energized by ciently charged. Hence,if a break of suflicient the circuit over cam contacts CHI which areopen at this time, accordingly additional actuations of detector DNSoperate relay E only while the vehicle is actually passing over thedetector pad. Operation of relay E at armature e2 completes a circuitover cam contacts 05, low resistance YD to shunt the condenser QJ, andthusextends the time which will be required for the condenser QJ to becharged to the striking voltage of the lamp FJ. Upon an actuation of thedetector DEW in position 6 the maximum timing circuit involvingcondenser QK becomes effective as it did in similar fashion uponactuation of detector DNS in position 3 to prevent the street havingright 01' way from holding right of way more than a predetermined periodagainst a. vehicle waiting onthe other street. The charging circuit forcondenser QK extends over contacts Cl, switch MNS, resistance 2|,condenser QK, contacts C6, and armature (12. The cycle of operationdescribed repeats itself in accordance with traffic conditions aspointed out.

It is assumed in the present case that the road NS is the main roadextending through the various intersections and it will be seen from thefact that cam contacts C8 are only opened in position 6 that if thereshould be a continuous stream of tratlic coming from the road EW, thatis the side road, during the EW right of way period, camshaft positions2 and 3, the main road will receive right of way as soon as thecondenser 'QK becomes sufficiently charged in position 3." This transferwill take place because relay K which also operates the solenoid S overarmature Icl has its operating circuit completed over contacts C8 inposition 3 of the cam shaft. In the case, however, of continuous trafllcon the main road, that is NS, in the NS right of way period, withtraflic waiting on the side road EW, even though the condenser QKbecomes sufliciently charged it is impossible for it to dischargethrough relay, K and neon lamp FK until the instant at which a pulse isreceived from the master timer to energize relay C and operate armaturec l. Accordingly if the trafhe on the main road is substantiallycontinuous so that the individual controllers are working on theirmaximum periods, the actual instants at which the various controllerswithdraw right of way from the main road are controlled by the mastercontroller and thus may be adjusted in phase to permit main road trafllcto proceed with the minimum-delay.

It will be noted that armatures d3 and e! when operated serve to includeresistances YF and YG in their respective amber timing circuits so that.

when right of way is being forcibly removed an additional amber periodis given to facilitate clearing the crossing. Similar control may beobtained by'means' of the'manual amber extension switches ENS, EEW.

The switches PNS and PEW are so-called arterial switches and whenoperated ensure that right of way shall return to the associated streetin the absence of tramc thereon. Their effect is to simulate theoperation of the pads at a time when the street in question is notreceiving right or .way, though'they do not produce any extension effectwhen the street already has right of way. i

For example if switch FEW is closed relay D will be energized by acircuit over switch PEW,

cam contacts 01 to minus.which circuit will be completed in all thepositions in which cam contacts C1 are closed; via, all camshaftpositions except the EW vehicle interval, position 3. In position 3relay'D will be operated by detector 'DEW actuations only, and in themanner described when switch PEW is not closed. Simi- 5 larLv, when PNSis closed, relay E is energized by a circuit over switch PNS and camcontacts Oil to minus in all cam shaft positions except the NS vehicleinterval in which contacts Cl! are open. switches PNS and PEW ,may beplaced in the closed position as desired to energize the correspondingdetector relay in all positions except its vehicle interval so as toreturn right of way to its respective street, butproduce no right'of wayextension.

The solenoid S is provided with three sets of contact springs 01 whichsl and s2 serve to shunt condensers GM and QK by low resistances YJ andYK respectively. (Springs 83 are effective in conjunction with armature1:2 to ensure that without any further operation of the associateddetector right of way shall be returned to the street from which it hasbeen forcibly removed.)

It will be understood that the master timer and associatedcontrol relaysare operated continuously vso that relay C in each individual controlleris operated once each cycle. This operation only produces any effecthowever if the traflic on the main road is so heavy'as to run thecontrollers up to'their maximum timing periods.

It was a feature of the system described above that the time intervalscould be extended beyond their initial periods in accordance with thevolume of trafllc passing over the road pads. This was achievedby'arranging for the road pads when operatedto shunt the condenser byway of a resistance thereby producing a partial discharge of thecondenser and a corresponding increase in the time taken for it toattain the 40 striking. voltage of the lamp. Since the length of timethe road pad remains, operated is inversely proportional to the speed ofthe vehicle, it follows that the degree 01' dischargeoi' the condenserand hence the time which the interval is extended will be commensuratewith that speed.

The operation 0! this arrangement will be better appreciated byreference to Fig. 3 of the drawings. It will be appreciated that iiright of way has remainedwithione of the roads for an appreciable time,and in the absence of traiilc on any or the roads, the coj ndenser QJwill be charged to the lull voltagecf the supply, which is assumed to beof the order of 400 volts. Ii now the road EW has right of way and avehicle crosses one of the associated road pads DEW the correspondingroad relay 1) will be operated to bring about the shunting oi thecondenser QJ by way of the resistance YE which is of. the order of 2000ohms.- Almost instantaneously the voltage across the condenser QA islowered below 260 volts which is assumed to be the striking voltage, orthreshold EMF tor conduction, (i. e. the voltage at which the lampbegins to be conducting) oi the neon lamp FJ, thereby ensuring anextension of the right of way interval since the lamp E! cannot strikeimmediately if relay E is now operated due to the presence of a vehicleon the road NS. If the vehicle is moving at a slow speed, the dischargeof the condenser will continue for .an appreciable period until thewheels leave the road pad so that the extension may be commensurate withthe speed.

It has been assumed in the design of the equipment under considerationthat the maximum Accordingly one or the other of.

speed at which a vehicle will ever pass the crossing will be in theneighborhood of 60 miles an hour, and the value of the dischargeresistance YE has been suitably chosen to enable the condenser to bedischarged just below 260 volts by a vehicle travelling at this speed.

In these circumstances thereto of discharge of the condenser is fairlyconstant for vehicle speeds from 60 down to about 30 miles an hour, butfor speeds below 30 miles an hour the rate oi discharge 'i'alls oi!appreciably or in other words the characteristic curve departs more andmore from a st'raight'line.

In general the speed at which vehicles will pass the crossing willprobably be below 25 miles an hour, and since as has been shown the rateof .discharge is rapidly falling oil for such speeds the diflerence inreduction of potential across the condenser for speeds of 30 miles anhour and 5 miles an hour will not be nearly so great as the diilerencein the reduction in potential for speeds 01.55 miles an hour and 30miles an hour. In

other words the variation oi the interval extension with speed is not sosensitive for vehicles travelling at average speed as for vehiclestravelllng' at high speed, and since the latter are without doubt theexception, the arrangement could with advantage be transposed.

The most obvious way to obtain an improvement is to increase the valueof resistance YE considerably, for example, up to 8000 ohms, which.

has the effect of altering the shape of the curve so that the averagespeed range is shifted on to the straight portion into somewhat theposition previously occupied by the high speed range. This expedient hasthe disadvantage however oi displacing the high speed range to such anextent that vehicles travelling at speeds above about 30 miles an hourare unable to discharge the condenser below the striking voltage 260,and

consequently they are unable to produce an extension of the timeinterval.

To overcome this disadvantage it is necessary to provide some meanswhich will enable the high speed vehicles to discharge the condenser tojust below the critical voltage of 260 regardless of their speed, sothat in eilect all the vehicles in the high speed range will receive afixed extension which will be suitably chosen so as to be adequate forthe slowest vehicles in this range.

It. is important however to ensure that the means which brings about theinstantaneous discharge oi the condenserto a fixed voltage will cease tobe operative when that voltage has. been attained, since otherwise itwill interfere with the operation '01 the average speed extensionarrangements.

According to the invention this is achieved by connecting a gasdischarge tube in parallel with the 8000 ohm discharge resistance, thecharacteristics of the tube being such that it will cease to glow at avoltage lust below 260 volts. This arrangement is shown in the Fig. 4which represents the application of the invention to Fig. 3,0! thedrawings the additional lamps PD and PE employed according to theinvention being conhected across the resistances YD and YE respectively.Operation of the device embodying the invention will be the same asoperation of the controller of Figure 3 except in thevehicle intervalpositions. that the camshaft is in theEW vehicle interval position 3cams'CIB and ClTare closed and if there has been no traiiic for sometime condenser QJ will be charged to the lull voltage; 01' aboutAssuming for example, then,

400. If a vehicle now arrives on the EW road, relay D will operate, andthe lamp FE will immediately strike and reduce the potential across thecondenser to its extinguishing voltage whereupon the lamp ceases to passcurrent. If relay D remains operated for a longer time because thevehicle is slow moving, further discharge of the condenser will takeplace through the resistance YE in the usual way. Similarly in the NSvehicle interval position Ii, if condenser QJ is, charged nearly to thefull voltage 9. NS vehicle actuation causing operation of relay Eimmediately causes the tube FD to strike and it this actuation continuesfor any appreciable time further discharge of condenser QJ thruresistance YD is produced in the usual way. It is desirable that theextinguishing voltage of the lamps FDv and FE should be appreciablybelow the striking voltage or the lamp FJ in order that even a very fastmoving vehicle which actuates the detector for a short time willdischarge the condenser below the striking voltage oi. the lamp FJ.

In case it should be necessary to control the rapid discharge or thecondenser to the fixed voltage an adjustable resistance couldconveniently be connected in series with the lamp with known results.

Summarizing briefly the operation of the tubes or lamps FD and FE, withparticular reference .to Fig. 4, in conjunction with the tube FJ, itwill be understood that the striking voltage or threshold E. M. F. oi.FD and FE is higher than that r FJ, and the cut-off E. M. r. of FD andFE is somewhat below the striking voltage of FJ. When the right of wayis on the NS street, condenser QJ cooperates with tube FJ to time theminimum .period. Condenser QJ is 01' course subject to resetting, inthe' building up of its charge, by NS vehicles operating relay E to"shunt QJ with low resistance YD over contacts I C5 and armature e".Since FD has a high threshold value it is not operative unless thecharge on the condenser rises above this high threshold value. At theend of the minimum period if relay E has not been operated by NSvehicles and ii' relay D has been operated by an approaching EW vehicle,the circuit thru tube FJ and relay J shunting condenser QJ will becompleted at armature di and the tube and relay J will be operated bythe condenser charge to advance the camshaft to its next position. If noEW vehicle has arrived by the end of this minimum period, however, theshunt circuit thru the tubeFJ will remain open, the charge on QJ risingabove the threshold E. M. F. of FJ toward line voltage in the absence ofNS vehicle actuation. If a NS vehicle now causes armature e2 momentarilyto shunt QJ over contacts 05, resistance YD and tube FD, the charge onQJ 'will immediately cause FD to flash and the charge on QJ will belowered to the value at which FD is no longer conducting, which is-avalue..under the thresholdipotential oi'tube FJ. Consequently such a NSvehicle will have time to cross the intersection before FJ can strike itd2 should be .closed by an EW vehicle at this time. Should the NS,actuation en- :ergizing relay E be of any appreciable length so that e2is still closed after-FD has extinguished,

discharge of condenser QJ below this value takes place thru resistanceYD in the usual way.

circuit including means for efiecting closure of the last said circuitacross said condenser and also including a gas discharge tube having aminimum potential below which conduction through the tube ceases, saidminimum potential being'below said particular potential where by uponsuch closure of the discharge circuit across the condenser when thecondenser potenthe resistance, the combination of a discharge tial isabove said minimum potential 9. rapid discharge of the condenser to theminimum potential is secured so that for very short variable periods ofclosure 01' the discharge circuit the time required to charge thecondenser to the particular potential after any such periods of closureshall be approximately constant.

2. In an electrical timing apparatus having a condenser, a chargingcircuit including a resistance, a particular potential responsive deviceand switch connected in series and both across said N condenser, thetime period of said apparatus being determined by the time required tocharge the condenser to the particular potential through the resistance,a discharge circuit including closure means for connecting the last saidcircuit across said condenser and also including a gas of the condenserwhen the discharge circuit remains closed after the condenser has beendischarged to said minimum potential.

3. In an electrical timing apparatus having a condenser, a chargingcircuit including a resistance, a particular potential responsive deviceand switch connected in seriesand both across said condenser, the timeperiod of said apparatus being determined by the time required to chargethe condenser to the particular potential through the resistance, thecombination of a discharge circuit including means for connecting thelast said circuit across said condenser and also including a gasdischarge tube having a minimum potential below which conduction throughthe tube ceases, said minimum potential being below said particularpotential, and a high resistance in parallel with the discharge'tube foreffecting further discharge of the condenser at a slower rate when thedischarge circuit remains closed after the condenser has been dischargedto said minimum potential. v

4. In an electrical timing apparatus having a condenser, a chargingcircuit including a resist: ance, a particular potential responsivedevice and switch connected in series and both across said condenser,the time period of said apparatus being determined'by the time requiredto charge the condenser to the particular potential through theresistance, the combination of a discharge circuit including closuremeans for connecting the last said circuit across said condenser andalso includinga gas discharge tube having a-minimum potential belowwhich conduction through the tube ceases, said minimum potential beingbelow said particular potential, and a resistance in parallel with thedischarge tube for effecting fur- -ther discharge of the condenser whenthe dissistance' connectedin series, a gas discharge tube having athreshold E. M. F. value'ior conduction less than said source, a switchand a relay all connected in series and across said condenser, a controlcircuit including a lower resistance and a second discharge tube inparallel with said lower resistance, said second tube having a thresholdconducting E. M. F. value greater than the first tube, and means forconnecting said control circuit across said condenser;

6. An electrical timing apparatus comprising a source of E. M. F., acondenser and'a high resistance connected in series, a gas dischargetube having a threshold E. M. F. value for conduction less than saidsource, a switch and a relay all connected in series and across saidcondenser, a control circuit including a lower resistance and a seconddischarge tube in parallel with said lower resistance. said second tubehaving a threshold conducting E. M. F. value greater than the first andhaving a minimum E. M. F. for cessation of conduction lower than thethreshold E. M. F. oi the first tube, and means for connecting'saidcontrol circuit across said condenser.

7. An electrical timing apparatus comprising a source of E. M. F., acondenser and high resistance connected in series and to said source soas to vary the E. M. F. on said condenser over a period of time, a, gasdischarge tube having a threshold E. M. F. value for conduction lessthan said source and a relay connected in series, a switch foralternatively connecting said tube and relay across said condenser anddisconnecting the same from said condenser, said tube and relay beingoperated when so connected by said switch when the E. M. F. on saidcondenser reaches said threshold value and being unoperated to permitthe E. M. F. on said condenser to exceed said threshold value whendisconnected by said switch, a. control circuit including a lowerresistance and a second discharge tube in parallel with said lowerresistance, said second tube having a threshold conducting E. M. F.value greaterthan the first tube and a minimum E. M. F. value forcessation of conduction somewhat lower than the threshold E. M. F. ofsaid firsttube, and means for alternatively connecting said controlcircuit in shunt with said condenser and disconnecting the sametherefrom, whereby the time required for the E.,M. F. on said condenserand said first tube connected therewith to reach the threshold valueof'said first tube so that said first tube will pass current to operatethe relay will be varied in accordance with the proportions of time thatthe last named connecting means connects and disconnects said controlcircuit.

8,. A timing apparatus comprisinga source of E. M. F., a high resistanceand a condenser in a series, a gas discharge tube having a prgedeter-'mined threshold E. M. F. value for conduction, a,

relay and a control" switch in series with said 75 tube and all in shuntacross said condenser, said discharge tube control switch having an openand closed position and in its closed position completing a circuit forthe discharge of the condenser through the tube to operate the relaywhen the threshold and also including a means operable only upon.

the closure of said second switch when the con denser is charged abovethe threshold, E. M. F. to discharge the condenser very rapidly to apoint below the threshold E. M. F.

9. An electrical timing apparatus comprising a source of E. M. F., acondenser and a high resistance connected in series, a discharge tubehaving a threshold E. M. F. for conduction and a relay and a controlswitch connected in series and across the condenser, and a dischargecircuit including means operable only when the condenser potential isabove the threshold E. M. F. and said switch is open to reset thecondenser potential to a point below the threshold E. M. F.substantially instantaneously upon closure of the discharge circuit, andfurther means effective only when the condenser potential is below saidthreshold E. M. F. to discharge the condenser below said threshold E. MF. to an extent approxi- 1 mately proportional to the length of thedischarge circuit closure interval. 1

10. In a trafllc signal system having a trafllc actuatable means. aright of way signal to be displayed for the control of trafiic and meansfortiming'the period of display of said signal; the last said meanscomprising timingv apparatus in-' cluding a condenser, a circuit forcharging said.

switch all connected in series across the condenser, and a condenser.discharge circuit includ ing a second discharge tube having a thresholdE. M. F. greater than the first tube,a resistance in parallel withsaidsecond tube, and a second I control switch in series with saidsecond tube and its parallel resistance. said discharge circuitconnected inshunt with said condenser, said'trafllc actuatable meansconnected for operating said second control switch so as to produce apartial discharge of the condenser upon trafllc actuation and thusextending the signal display period until said condenser has againbecome charged to the threshold E. M. F. of the first tube, said secondassuring that momentary actua-. tion by trafilc will discharge saidcondenser. below the threshold E. M. F. of the first discharge tube inevent" that said condenser is charged to a higher E. M. F. when thefirst mentioned control switch is open.

11. In a traffic control system including a and a switch connected in'series and across said condenser, and adischarge circuit including alower resistance and a control switchin series and a second dischargetube in parallel with said aoaa'ma lower resistance, said second tubehaving a for causing the display of said right of way sig-.

nals for time periods for the control of tramc, the trailic actuatablemeans in one lane acting during condenser and a high resistanceconnected in series, a time interval terminating circuit including adischarge tube having a threshold E. M. F. for conduction, meansincluding a relay for 1 terminating the right of way signal period forsaid other lane and a normally open switch operated by the trafficactuatable means in said one lane, said tube, relay and switch allconnected in series across said condenser, and a discharge circuitincluding a lower resistance and a control switch in series, saidcontrol switch operated by the trathc actuatable means in said otherlane, and a second discharge tube in parallel with said lowerresistance, said second tube having a 15 the right of way period of theother lane to cause threshold E. M. F. greater than the first tube, saidtransfer of right of way from such other lane to discharge circuit beingconnectable across said said one lane by said timing apparatus at the.condenser to discharge the same and thus extend end of a time period,and the trafllc actuatable the right of way period in said other lane bymeans in the other lane acting upon actuation operation of the controlswitch which is operated 20 during said right of way period of saidother lane by actuation of the traflic actuatable means 'of to prolongsuch period to delay such transfer; said timing apparatus including asource of E. M. F., a

said other lane.

THOMAS PHILIP PREIST.

CERTIFICATE OF CORRECTION.

Patent No. 2,088,725

August 5, I957 THOMAS PHILIP PREIST It is hereby certified. that errorappears in the printed specification of the above numbered patentrequiring correction as follows: Page 1 second column, line 69, after'and" insert the words thereupon solenoids; page 5, first column, line57, for "switch EEW" read switch LEW; page 7, first column, line 141,for "armature 6 read armature e2; and that the said Letters Patentshould be read with these corrections therein thl the same may conformto the record of the case in the Patent Office,

Signed and sealed this 21st day of December, A, D. 1957.

Henry Van Arsdale,

Acting Commissioner of, Patents.

(Seal) aoaa'ma lower resistance, said second tube having a for causingthe display of said right of way sig-.

nals for time periods for the control of tramc, the trailic actuatablemeans in one lane acting during condenser and a high resistanceconnected in series, a time interval terminating circuit including adischarge tube having a threshold E. M. F. for conduction, meansincluding a relay for 1 terminating the right of way signal period forsaid other lane and a normally open switch operated by the trafficactuatable means in said one lane, said tube, relay and switch allconnected in series across said condenser, and a discharge circuitincluding a lower resistance and a control switch in series, saidcontrol switch operated by the trathc actuatable means in said otherlane, and a second discharge tube in parallel with said lowerresistance, said second tube having a 15 the right of way period of theother lane to cause threshold E. M. F. greater than the first tube, saidtransfer of right of way from such other lane to discharge circuit beingconnectable across said said one lane by said timing apparatus at the.condenser to discharge the same and thus extend end of a time period,and the trafllc actuatable the right of way period in said other lane bymeans in the other lane acting upon actuation operation of the controlswitch which is operated 20 during said right of way period of saidother lane by actuation of the traflic actuatable means 'of to prolongsuch period to delay such transfer; said timing apparatus including asource of E. M. F., a

said other lane.

THOMAS PHILIP PREIST.

CERTIFICATE OF CORRECTION.

Patent No. 2,088,725

August 5, I957 THOMAS PHILIP PREIST It is hereby certified. that errorappears in the printed specification of the above numbered patentrequiring correction as follows: Page 1 second column, line 69, after'and" insert the words thereupon solenoids; page 5, first column, line57, for "switch EEW" read switch LEW; page 7, first column, line 141,for "armature 6 read armature e2; and that the said Letters Patentshould be read with these corrections therein thl the same may conformto the record of the case in the Patent Office,

Signed and sealed this 21st day of December, A, D. 1957.

Henry Van Arsdale,

Acting Commissioner of, Patents.

(Seal)

